#include "freertos_heap_5.h"

/*----------------------------------------------------------------------------*/
#define configHEAP_CLEAR_MEMORY_ON_FREE    (0)

/*----------------------------------------------------------------------------*/
/* Block sizes must not get too small. */
#define heapMINIMUM_BLOCK_SIZE              ((size_t)(xHeapStructSize << 1))

/* Assumes 8bit bytes! */
#define heapBITS_PER_BYTE                   ((size_t)8)

/* Max value that fits in a size_t type. */
#define heapSIZE_MAX                        (~((size_t)0))

/* Check if multiplying a and b will result in overflow. */
#define heapMULTIPLY_WILL_OVERFLOW(a, b)    (((a) > 0) && ((b) > (heapSIZE_MAX / (a))))

/* Check if adding a and b will result in overflow. */
#define heapADD_WILL_OVERFLOW(a, b)         ((a) > ( heapSIZE_MAX - (b)))

/* MSB of the xBlockSize member of an BlockLink_t structure is used to track
 * the allocation status of a block.  When MSB of the xBlockSize member of
 * an BlockLink_t structure is set then the block belongs to the application.
 * When the bit is free the block is still part of the free heap space. */
#define heapBLOCK_ALLOCATED_BITMASK         (((size_t)1) << ((sizeof(size_t) * heapBITS_PER_BYTE) - 1))
#define heapBLOCK_SIZE_IS_VALID(xBlockSize) (((xBlockSize) & heapBLOCK_ALLOCATED_BITMASK) == 0)
#define heapBLOCK_IS_ALLOCATED(pxBlock)     (((pxBlock->xBlockSize) & heapBLOCK_ALLOCATED_BITMASK) != 0)
#define heapALLOCATE_BLOCK(pxBlock)         ((pxBlock->xBlockSize) |= heapBLOCK_ALLOCATED_BITMASK)
#define heapFREE_BLOCK(pxBlock)             ((pxBlock->xBlockSize) &= ~heapBLOCK_ALLOCATED_BITMASK)

/*----------------------------------------------------------------------------*/
/* Define the linked list structure.
 * This is used to link free blocks in order of their memory address. */
typedef struct A_BLOCK_LINK
{
    struct A_BLOCK_LINK * pxNextFreeBlock; /**< The next free block in the list. */
    size_t xBlockSize;                     /**< The size of the free block. */
} BlockLink_t;

/*----------------------------------------------------------------------------*/
/* The size of the structure placed at the beginning of each allocated memory
 * block must by correctly byte aligned. */
static const size_t xHeapStructSize = (sizeof(BlockLink_t) + ((size_t)(portBYTE_ALIGNMENT - 1))) & ~((size_t)portBYTE_ALIGNMENT_MASK);

/* Create a couple of list links to mark the start and end of the list. */
static BlockLink_t xStart;
static BlockLink_t * pxEnd = NULL;

/* Keeps track of the number of calls to allocate and free memory as well as the
 * number of free bytes remaining, but says nothing about fragmentation. */
static size_t xFreeBytesRemaining = 0U;
static size_t xMinimumEverFreeBytesRemaining = 0U;
static size_t xNumberOfSuccessfulAllocations = 0;
static size_t xNumberOfSuccessfulFrees = 0;

/*----------------------------------------------------------------------------*/
/*
 * Inserts a block of memory that is being freed into the correct position in
 * the list of free memory blocks.  The block being freed will be merged with
 * the block in front it and/or the block behind it if the memory blocks are
 * adjacent to each other.
 */
static void prvInsertBlockIntoFreeList(BlockLink_t * pxBlockToInsert);

/*----------------------------------------------------------------------------*/
void * pvPortMalloc(size_t xWantedSize)
{
    BlockLink_t * pxBlock;
    BlockLink_t * pxPreviousBlock;
    BlockLink_t * pxNewBlockLink;
    void * pvReturn = NULL;
    size_t xAdditionalRequiredSize;

    /* The heap must be initialised before the first call to prvPortMalloc(). */
    configASSERT(pxEnd);

    if (xWantedSize > 0) {
        /* The wanted size must be increased so it can contain a BlockLink_t
         * structure in addition to the requested amount of bytes. */
        if (heapADD_WILL_OVERFLOW(xWantedSize, xHeapStructSize) == 0) {
            xWantedSize += xHeapStructSize;
            /* Ensure that blocks are always aligned to the required number  of bytes. */
            if ((xWantedSize & portBYTE_ALIGNMENT_MASK) != 0x00) {
                /* Byte alignment required. */
                xAdditionalRequiredSize = portBYTE_ALIGNMENT - (xWantedSize & portBYTE_ALIGNMENT_MASK);
                if (heapADD_WILL_OVERFLOW(xWantedSize, xAdditionalRequiredSize) == 0) {
                    xWantedSize += xAdditionalRequiredSize;
                } else {
                    xWantedSize = 0;
                }
            }
        } else {
            xWantedSize = 0;
        }
    }


    /* Check the block size we are trying to allocate is not so large that the
     * top bit is set.  The top bit of the block size member of the BlockLink_t
     * structure is used to determine who owns the block - the application or
     * the kernel, so it must be free. */
    if (heapBLOCK_SIZE_IS_VALID(xWantedSize) != 0) {
        if ((xWantedSize > 0) && (xWantedSize <= xFreeBytesRemaining)) {
            /* Traverse the list from the start (lowest address) block until
             * one of adequate size is found. */
            pxPreviousBlock = &xStart;
            pxBlock = xStart.pxNextFreeBlock;

            while ((pxBlock->xBlockSize < xWantedSize) &&
                   (pxBlock->pxNextFreeBlock != NULL)) {
                pxPreviousBlock = pxBlock;
                pxBlock = pxBlock->pxNextFreeBlock;
            }

            /* If the end marker was reached then a block of adequate size was not found. */
            if (pxBlock != pxEnd) {
                /* Return the memory space pointed to - jumping over the
                 * BlockLink_t structure at its start. */
                pvReturn = (void *) (((uint8_t *) pxPreviousBlock->pxNextFreeBlock) + xHeapStructSize);

                /* This block is being returned for use so must be taken out
                 * of the list of free blocks. */
                pxPreviousBlock->pxNextFreeBlock = pxBlock->pxNextFreeBlock;

                /* If the block is larger than required it can be split into two. */
                if ((pxBlock->xBlockSize - xWantedSize) > heapMINIMUM_BLOCK_SIZE) {
                    /* This block is to be split into two.  Create a new
                     * block following the number of bytes requested. The void
                     * cast is used to prevent byte alignment warnings from the
                     * compiler. */
                    pxNewBlockLink = (void *) (((uint8_t *) pxBlock) + xWantedSize);

                    /* Calculate the sizes of two blocks split from the single block. */
                    pxNewBlockLink->xBlockSize = pxBlock->xBlockSize - xWantedSize;
                    pxBlock->xBlockSize = xWantedSize;

                    /* Insert the new block into the list of free blocks. */
                    pxNewBlockLink->pxNextFreeBlock = pxPreviousBlock->pxNextFreeBlock;
                    pxPreviousBlock->pxNextFreeBlock = pxNewBlockLink;
                }

                xFreeBytesRemaining -= pxBlock->xBlockSize;

                if (xFreeBytesRemaining < xMinimumEverFreeBytesRemaining) {
                    xMinimumEverFreeBytesRemaining = xFreeBytesRemaining;
                }

                /* The block is being returned - it is allocated and owned
                 * by the application and has no "next" block. */
                heapALLOCATE_BLOCK(pxBlock);
                pxBlock->pxNextFreeBlock = NULL;
                xNumberOfSuccessfulAllocations++;
            }
        }
    }

    traceMALLOC(pvReturn, xWantedSize);

#if (configUSE_MALLOC_FAILED_HOOK == 1)
    if (pvReturn == NULL) {
        vApplicationMallocFailedHook();
    }
#endif /* configUSE_MALLOC_FAILED_HOOK == 1 */

    return pvReturn;
}

/*----------------------------------------------------------------------------*/
void vPortFree(void * pv)
{
    uint8_t * puc = (uint8_t *) pv;
    BlockLink_t * pxLink;

    if (pv != NULL) {
        /* The memory being freed will have an BlockLink_t structure immediately
         * before it. */
        puc -= xHeapStructSize;

        /* This casting is to keep the compiler from issuing warnings. */
        pxLink = (void *) puc;

        configASSERT(heapBLOCK_IS_ALLOCATED(pxLink) != 0);
        configASSERT(pxLink->pxNextFreeBlock == NULL);

        if (heapBLOCK_IS_ALLOCATED(pxLink) != 0) {
            if (pxLink->pxNextFreeBlock == NULL) {
                /* The block is being returned to the heap - it is no longer allocated. */
                heapFREE_BLOCK(pxLink);
#if (configHEAP_CLEAR_MEMORY_ON_FREE == 1)
                (void)memset(puc + xHeapStructSize, 0, pxLink->xBlockSize - xHeapStructSize);
#endif

                /* Add this block to the list of free blocks. */
                xFreeBytesRemaining += pxLink->xBlockSize;
                traceFREE(pv, pxLink->xBlockSize);
                prvInsertBlockIntoFreeList(((BlockLink_t *) pxLink));
                xNumberOfSuccessfulFrees++;
            }
        }
    }
}

/*----------------------------------------------------------------------------*/
void * pvPortCalloc(size_t xNum, size_t xSize)
{
    void * pv = NULL;

    if (heapMULTIPLY_WILL_OVERFLOW(xNum, xSize) == 0) {
        pv = pvPortMalloc(xNum * xSize);
        if (pv != NULL) {
            (void) memset(pv, 0, xNum * xSize);
        }
    }

    return pv;
}

/*----------------------------------------------------------------------------*/
size_t xPortGetFreeHeapSize(void)
{
    return xFreeBytesRemaining;
}

/*----------------------------------------------------------------------------*/
size_t xPortGetMinimumEverFreeHeapSize(void)
{
    return xMinimumEverFreeBytesRemaining;
}

/*----------------------------------------------------------------------------*/
static void prvInsertBlockIntoFreeList(BlockLink_t * pxBlockToInsert)
{
    BlockLink_t * pxIterator;
    uint8_t * puc;

    /* Iterate through the list until a block is found that has a higher address
     * than the block being inserted. */
    for (pxIterator = &xStart;
         pxIterator->pxNextFreeBlock < pxBlockToInsert;
         pxIterator = pxIterator->pxNextFreeBlock) {
        /* Nothing to do here, just iterate to the right position. */
    }

    /* Do the block being inserted, and the block it is being inserted after
     * make a contiguous block of memory? */
    puc = (uint8_t *) pxIterator;

    if ((puc + pxIterator->xBlockSize) == (uint8_t *) pxBlockToInsert) {
        pxIterator->xBlockSize += pxBlockToInsert->xBlockSize;
        pxBlockToInsert = pxIterator;
    }

    /* Do the block being inserted, and the block it is being inserted before
     * make a contiguous block of memory? */
    puc = (uint8_t *) pxBlockToInsert;

    if((puc + pxBlockToInsert->xBlockSize) == (uint8_t *)pxIterator->pxNextFreeBlock) {
        if (pxIterator->pxNextFreeBlock != pxEnd) {
            /* Form one big block from the two blocks. */
            pxBlockToInsert->xBlockSize += pxIterator->pxNextFreeBlock->xBlockSize;
            pxBlockToInsert->pxNextFreeBlock = pxIterator->pxNextFreeBlock->pxNextFreeBlock;
        } else {
            pxBlockToInsert->pxNextFreeBlock = pxEnd;
        }
    } else {
        pxBlockToInsert->pxNextFreeBlock = pxIterator->pxNextFreeBlock;
    }

    /* If the block being inserted plugged a gab, so was merged with the block
     * before and the block after, then it's pxNextFreeBlock pointer will have
     * already been set, and should not be set here as that would make it point
     * to itself. */
    if (pxIterator != pxBlockToInsert) {
        pxIterator->pxNextFreeBlock = pxBlockToInsert;
    }
}

/*----------------------------------------------------------------------------*/
void vPortDefineHeapRegions(const HeapRegion_t * const pxHeapRegions)
{
    BlockLink_t * pxFirstFreeBlockInRegion = NULL;
    BlockLink_t * pxPreviousFreeBlock;
    portPOINTER_SIZE_TYPE xAlignedHeap;
    size_t xTotalRegionSize, xTotalHeapSize = 0;
    BaseType_t xDefinedRegions = 0;
    portPOINTER_SIZE_TYPE xAddress;
    const HeapRegion_t * pxHeapRegion;

    /* Can only call once! */
    configASSERT(pxEnd == NULL);

    pxHeapRegion = &(pxHeapRegions[xDefinedRegions]);

    while (pxHeapRegion->xSizeInBytes > 0) {
        xTotalRegionSize = pxHeapRegion->xSizeInBytes;

        /* Ensure the heap region starts on a correctly aligned boundary. */
        xAddress = (portPOINTER_SIZE_TYPE)pxHeapRegion->pucStartAddress;
        if ((xAddress & portBYTE_ALIGNMENT_MASK) != 0) {
            xAddress += ( portBYTE_ALIGNMENT - 1 );
            xAddress &= ~portBYTE_ALIGNMENT_MASK;
            /* Adjust the size for the bytes lost to alignment. */
            xTotalRegionSize -= (size_t)(xAddress - (portPOINTER_SIZE_TYPE)pxHeapRegion->pucStartAddress);
        }

        xAlignedHeap = xAddress;

        /* Set xStart if it has not already been set. */
        if (xDefinedRegions == 0) {
            /* xStart is used to hold a pointer to the first item in the list of
             * free blocks.  The void cast is used to prevent compiler warnings. */
            xStart.pxNextFreeBlock = (BlockLink_t *)xAlignedHeap;
            xStart.xBlockSize = (size_t)0;
        } else {
            /* Should only get here if one region has already been added to the heap. */
            configASSERT(pxEnd != NULL);
            /* Check blocks are passed in with increasing start addresses. */
            configASSERT((size_t) xAddress > (size_t) pxEnd);
        }

        /* Remember the location of the end marker in the previous region, if any. */
        pxPreviousFreeBlock = pxEnd;

        /* pxEnd is used to mark the end of the list of free blocks and is
         * inserted at the end of the region space. */
        xAddress = xAlignedHeap + (portPOINTER_SIZE_TYPE)xTotalRegionSize;
        xAddress -= (portPOINTER_SIZE_TYPE)xHeapStructSize;
        xAddress &= ~((portPOINTER_SIZE_TYPE)portBYTE_ALIGNMENT_MASK);
        pxEnd = (BlockLink_t *)xAddress;
        pxEnd->xBlockSize = 0;
        pxEnd->pxNextFreeBlock = NULL;

        /* To start with there is a single free block in this region that is
         * sized to take up the entire heap region minus the space taken by the
         * free block structure. */
        pxFirstFreeBlockInRegion = (BlockLink_t *) xAlignedHeap;
        pxFirstFreeBlockInRegion->xBlockSize = (size_t)(xAddress - (portPOINTER_SIZE_TYPE)pxFirstFreeBlockInRegion);
        pxFirstFreeBlockInRegion->pxNextFreeBlock = pxEnd;

        /* If this is not the first region that makes up the entire heap space
         * then link the previous region to this region. */
        if (pxPreviousFreeBlock != NULL) {
            pxPreviousFreeBlock->pxNextFreeBlock = pxFirstFreeBlockInRegion;
        }

        xTotalHeapSize += pxFirstFreeBlockInRegion->xBlockSize;

        /* Move onto the next HeapRegion_t structure. */
        xDefinedRegions++;
        pxHeapRegion = &(pxHeapRegions[xDefinedRegions]);
    }

    xMinimumEverFreeBytesRemaining = xTotalHeapSize;
    xFreeBytesRemaining = xTotalHeapSize;

    /* Check something was actually defined before it is accessed. */
    configASSERT(xTotalHeapSize);
}

/*----------------------------------------------------------------------------*/
void vPortGetHeapStats(HeapStats_t * pxHeapStats)
{
    BlockLink_t * pxBlock = xStart.pxNextFreeBlock;
    size_t xMinSize = portMAX_DELAY; /* 最小块大小 */
    size_t xMaxSize = 0;             /* 最大块大小 */
    size_t xBlocks = 0;              /* 块个数 */

    /* 如果堆没有初始化, pxBlock将为NULL. 堆在第一次分配时自动初始化. */
    if (pxBlock != NULL) {
        while (pxBlock != pxEnd) {
            /* 增加块的数量, 并记录到目前为止看到的最大块. */
            xBlocks++;
            if (pxBlock->xBlockSize > xMaxSize) {
                xMaxSize = pxBlock->xBlockSize;
            }

            /**
             * 堆5在每个区域的末尾都有一个零大小的块 - 这个块只用于链接到下一个堆区域,
             * 所以它不是一个真正的块.
             */
            if (pxBlock->xBlockSize != 0) {
                if (pxBlock->xBlockSize < xMinSize) {
                    xMinSize = pxBlock->xBlockSize;
                }
            }

            /* 移动到链中的下一个区块, 直到到达最后一个区块. */
            pxBlock = pxBlock->pxNextFreeBlock;
        }
    }

    pxHeapStats->xSizeOfLargestFreeBlockInBytes = xMaxSize;
    pxHeapStats->xSizeOfSmallestFreeBlockInBytes = xMinSize;
    pxHeapStats->xNumberOfFreeBlocks = xBlocks;

    pxHeapStats->xAvailableHeapSpaceInBytes = xFreeBytesRemaining;
    pxHeapStats->xNumberOfSuccessfulAllocations = xNumberOfSuccessfulAllocations;
    pxHeapStats->xNumberOfSuccessfulFrees = xNumberOfSuccessfulFrees;
    pxHeapStats->xMinimumEverFreeBytesRemaining = xMinimumEverFreeBytesRemaining;
}

/*----------------------------------------------------------------------------*/
